1. Field of the Invention
The invention generally relates to satellite television network broadcasts and more specifically to a method and system of inserting auxiliary data packets into a single or multi-channel DSS bitstream in a real-time manner.
2. Description of the Prior Art
In traditional television broadcast systems, it is often desirable to restrict the number of accessible television channels to only those subscribers who actually pay for the particular channels. The same restrictions apply to interactive satellite television broadcasts. If, for example, a subscriber does not have access to HBO, or CNN, it is desirable to insure that the user cannot access these channels and to inform the user that although he or she does not presently have access to these service channels, they can order the channels by following ordering instructions. These security measures and the ordering information are presented to the user via traditional satellite broadcasts.
The security measures and additional service channel information are broadcast in the form of security or auxiliary data packets and must be inserted into the traditional satellite uplink broadcasts via what is know in the art as head-end platforms. The goal is to prevent the user from viewing channels that he or she has not paid to see and to allow the user to order the channels if he or she so desires. The user should be presented with a television screen full of content, without “dead time” (i.e. a blank screen), whether it be actual programming content, or advertisements or instructions prompting the user to subscribe to additional service channels.
The data packets are placed in auxiliary data packet placeholders, which are inserted at the appropriate rate into an application stream to be included in a traditional satellite uplink subsystem. However, the insertion of these security data packets or data packet placeholders at the appropriate rate is not an easy task. The computer operator must insert enough data packets in order to insure that the user is not viewing a blank television screen. The operator is also limited by bandwidth constraints since the data packets are identical and multiple insertions are merely a waste of valuable bandwidth. The rate of insertion of these data packets is therefore critical. If the insertion rate is too slow and not enough data packets are present in the satellite broadcast, then the end user, when he or she tunes to that specific channel, may be looking at a blank screen, devoid of any information since it is the information contained in the data packets that the user sees first. If too many data packets are inserted, it is a waste of the bandwidth of the transmission because each data packet contains essentially the identical information.
Presently, systems exist that have the capability to insert security or auxiliary data packets or data packet placeholders into a stream of data comprised of one service channel that will be part of the uplink system of a traditional satellite broadcast. In a stream comprised of a single service channel, this is not difficult since the operator need only be aware of the bit rate for the service channel and the number of auxiliary packets to insert per second, to derive the insertion rate. Because the bit rate of a multiplexed data file having a single service channel must necessarily equal the bit rate of the multiplexed file itself, the parameters are known and the real time insertion of data packets can be performed.
However, the bit rate of the data stream is rarely a constant. This rate may often change as will the number of service channels within the bitstream. Therefore, a service operator cannot set the data packet insertion rate and expect this rate to apply for all data streams.
Problems also arise when software programmers attempt to insert these data packets into a multiplexed data file comprised of more than one service channel. In this scenario, the aggregate bit rate of the entire data stream is known, but the bit rate of each individual service channel is unknown. The service operator cannot rely on his knowledge of the aggregate bit rate for the entire data stream, since each service channel bitstream within the total datastream has its own bit rate.
In the prior art, the only way the operator would be able to discern the number of packets that would correspond to each service channel if he were to be provided with this additional information. For example, if the operator knew that 10% of all data packets would go into service channel 1 and 25% would go into service channel 2, then the data packet allocation could be performed. But this would require the operator to be aware of this additional information. The goal is to achieve the result of proper data packet or data packet placeholder insertion without the need for any additional information. Therefore, the prior art methods cannot apply to multiple channel data streams.
It could be argued that the broadcast subsystem could be reconfigured to accept not only the bit rate for the entire multiplexed file, but also the bit rates of the individual service channels. This approach has a number of drawbacks. In particular, it leaves it up to a human operator to ensure that not only the individual bit rates are correct, but that they also correctly add up to the aggregate. The chance for human error is great and increases based upon the number of service channels, each having its own unique bit rate, within the entire data stream. This approach does not lend itself to automation, and in the fast-paced world of satellite broadcasts, automation is critical.
Accordingly, what is needed in the art is a system and method designed to automatically insert auxiliary head-end data packet placeholders in single or multiple channel data stream regardless of the number of service channels comprising the data stream, for the later insertion of data packets in conventional satellite television broadcasts.
It is, therefore, to the effective resolution of the aforementioned problems and shortcomings of the prior art that the present invention is directed.